Motor gear box with grommets

ABSTRACT

A motor gear box has a direct current motor, a first bevel gear, a second bevel gear, a pinion transfer gear, at least one cluster gear, an output gear, an output shaft, and a collar abutting against the output gear and surrounding the output shaft. The motor gear box also includes a frame formed integrally with the collar, a first cover to protect the motor, and a second cover having a cradle formed integrally therein. The output shaft has at one end a stepped down shaft portion held in the cradle and at an opposite end a hollow internal chamber formed to receive a protuberance of a device requiring the delivery of high torque to carry out a task in a small space. A programmable control board is attached to one side of the motor; an electrode tip is arranged on a top of the motor; a lead harness assembly is secured around the electrode tip; and an L-shaped connection rod links the lead harness assembly to the control board to conserve space. A housing contains the direct current motor and has plural mounting tabs. A grommet is secured in each of the plural mounting tabs. The purpose of the grommets is to minimize noise and vibrations caused by high speed rotation of the direct current motor inside the housing.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of prior U.S. patentapplication Ser. No. 10/136,325 filed on May 2, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to machine elements and mechanismsgenerally, but more particularly to motor gear boxes.

[0004] 2. Description of the Related Art

[0005] The present invention is an improvement upon the compactminiature motor gear box shown in U.S. Utility Pat. No. 6,054,785 whichwas issued on Apr. 25, 2000, to Kerdjoudj et al. and in U.S. Design Pat.No. D440,995 which was issued on Apr. 24, 2001, to Tsergas et al.

[0006]FIG. 1 shows a bottom plan view of a prior art motor gear box 100with built-in mounting brackets 168 at each end. A separate sleeve 102surrounds an output shaft (not shown) that protrudes from the gear box100.

[0007]FIG. 2 shows a cross-sectional side elevational view of the priorart motor gear box 100 with the built-in mounting brackets 168 at eachend and the separate sleeve 102 which surrounds the output shaft (notshown) that protrudes from the gear box 100.

[0008]FIG. 3 shows a cutaway top plan view taken along line 3-3 of FIG.2 showing the prior art motor gear box 100 with the separate sleeve 102and other sleeves 104, 106 and 108 interconnected by reinforcing ribs103, 105 and 107, respectively. These other sleeves 104, 106 and 108surround other gear shafts (not shown). Other reinforcing ribs 109, 111,112 and 113 provide rigidity to a frame 114 which surrounds the sleevesand ribs mentioned above.

[0009]FIG. 4 shows another cutaway top plan view taken along line 4-4 ofFIG. 2 showing the prior art motor gear box 100 with the frame 114surrounding a direct current (DC) motor 110. A programmable controlboard (PCB) 122 is mounted on a rear end 130 of the DC motor 110 while afirst-stage worm gear 132 protrudes from a front end 120 of the DC motor110. This first-stage worm gear 132 meshes with a double pinion transfergear 134.

[0010]FIG. 8 shows a bottom plan view of another prior art motor gearbox 200 with built-in mounting tabs 268 at each corner. A separatesleeve 202 surrounds an output shaft (not shown) that protrudes from thegear box 200. A housing 214 contains the DC motor 10 of FIGS. 5 and 6and includes in FIG. 8 a dome 250 which protects a second gear pin 50(see FIG. 6) inside the gear box 200. Each mounting tab 268 has athrough hole 204 which is partially surrounded by a curved wall 206 thatserves to protect a screw or a bolt (not shown) which passes through thehole 204.

SUMMARY OF THE INVENTION

[0011] The present invention relates to a gear box housing a motorcapable of delivering a high torque sufficient to crush ice in arefrigerator ice maker.

[0012] This arrangement keeps the motor compact inside the gear boxwhich makes efficient use of space in a refrigerator and any otherappliance requiring the application of high torque in a small space.

[0013] A number of features support quiet operation for thissubfractional horsepower motor inside the gear box of the presentinvention.

[0014] A primary object of the present invention is to provide a leadharness assembly and a connection for linking an electrode tip at oneend of a direct current (DC) motor to a programmable control board (PCB)mounted on a side of the DC motor to conserve space.

[0015] A secondary object of the present invention is to provide twobevel gears which are stronger than a single worm gear for meshing witheach other and for transmitting more power from the DC motor to anoutput shaft.

[0016] A tertiary object of the present invention is to provide a collarformed integrally with the frame so that a stronger output shaft mayprotrude therefrom. Such a stronger output shaft is capable of applyinghigher torque than a conventional shaft to a task requiring greatstrength, such as crushing ice cubes and chips inside a refrigerator icemaker.

[0017] Another object of the present invention is to provide grommetsplaced in the holes of the mounting tabs on four corners of the housingthat contains the DC motor in order to minimize noise and vibrationstransmitted from the DC motor to the refrigerator ice maker. This noiseand the vibrations are caused by the high speed rotation of the DC motorinside the housing.

[0018] These and other objects of the present invention will be betterunderstood by reference to the following drawings and the subsequentdetailed description when considered together.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 shows a bottom plan view of a prior art motor gear box.

[0020]FIG. 2 shows a cross-sectional side elevational view of the priorart motor gear box.

[0021]FIG. 3 shows a top plan view taken along line 3-3 of FIG. 2.

[0022]FIG. 4 shows a top plan view taken along line 4-4 of FIG. 2.

[0023]FIG. 5 shows a cutaway top plan view of the present invention.

[0024]FIG. 6 shows a cross-sectional side elevational view of thepresent invention.

[0025]FIG. 7A shows a bottom plan view of an output gear of the presentinvention.

[0026]FIG. 7B is a cross-sectional view taken along line 7B-7B of FIG.7A.

[0027]FIG. 7C is a top plan view of an output shaft taken along line7C-7C of FIG. 7B.

[0028]FIG. 8 is a bottom plan view of a second prior art motor gear box.

[0029]FIG. 9A is a bottom plan view of a second embodiment of thepresent invention.

[0030]FIG. 9B is a cross-sectional view taken along line 9B-9B of FIG.9A.

DETAILED DESCRIPTION OF THE INVENTION

[0031] Like reference numerals designate identical or correspondingparts throughout the several views of the drawings. Features of theinvention will become apparent in the course of the followingdescription of a preferred embodiment which is given only forillustration of the invention and which is not intended to be limitingthereof.

[0032] In FIG. 5, a DC motor 10 is attached inside a gear box 11 havinga frame 14 surrounding the motor 10. A plurality of straight side tabs18 interlock the frame 14 to a first cover (not shown in FIG. 5) whichprotects the motor 10 inside the gear box 11. A programmable controlboard (PCB) 22 is attached to one side of the motor 10 to conservespace. Attachment to a top 75, a bottom 85, or another side of the motor10 would require the gear box 11 to be made larger in order toaccommodate the motor 10 in its illustrated position at an angle withthe PCB 22 attached thereto.

[0033] A lead harness assembly 24 is secured around an electrode tip 80arranged on the top 75 of the motor 10 and links the electrode tip 80 atthe top 75 of the motor 10 via an L-shaped connection rod 28 to the PCB22 mounted on one side of the motor 10.

[0034] The gear box 11 has a pair of triangular corner feet 68 whichallow the entire unit to be mounted to the device being operated.

[0035] The PCB 22 has attached thereto an electrolytic capacitor 26 forfiltering constant direct current, a plurality of diodes (not shown)forming a full-wave bridge, and a motor fuse 30 which is preferably apositive temperature coefficient (PTC) resistor.

[0036] Alternating current (AC) voltage enters the PCB 22 at one end andis received by a header 60 mounted on the PCB 22 before exiting toenergize the motor 10. After leaving the header 60, the AC voltagepasses through the plurality of diodes (not shown) which form afull-wave bridge to rectify the AC voltage. After leaving the pluralityof diodes (not shown), the voltage is processed by the capacitor 26which is mounted to the PCB 22 and which filters for constant directcurrent. The voltage then goes through the PTC resistor which is alsomounted to the PCB 22 and which functions as the motor fuse 30 toprevent overloads. The voltage passes again through the header 60 beforereaching a switch (not shown) for reversing the current back through theheader 60 and out to the motor 10. The reversing switch (not shown) ismounted outside the PCB 22 to a second cover (also not shown in FIG. 5).

[0037] A small first bevel gear 32 is driven directly by the motor 10 atthe bottom 85 opposite from the electrode tip 80. This small drivingfirst bevel gear 32 meshes with a large driven second bevel gear 36having a longitudinal shaft 41.

[0038] In FIG. 6, the motor 10 has a permanent magnet 12 attachedthereto at the top 85 where the electrode tip 80 is located. Thispermanent magnet 12 produces an electromagnetic field necessary foroperating the motor 10. A first cover 16 on an outer side protects themotor 10 inside the gear box 11. A second cover 20 is attached to theframe 14 and is located on an inner side of the motor 10 which isprotected on the outer side by the first cover 16.

[0039] The driving first bevel gear 32 meshes with the driven secondbevel gear 36 which, in turn, drives a pinion transfer gear 34 moldedthereto at a right angle to one end thereof. At an opposite end of thetransfer gear 34, teeth 38 are formed in a side thereof and changerotation from a right angle to a plurality of cluster gears which arealigned parallel to the driving first bevel gear 32. An internaltrunnion 40 makes the driven second bevel gear 36 stable while anotherinternal trunnion 42 makes the transfer gear 34 stable by extendingtherein and engaging longitudinal shafts 41 and 43, respectively, fromopposite ends. The one trunnion 40 is molded at one end to the firstcover 16 while the other trunnion 42 is molded at its opposite end tothe frame 14.

[0040] The teeth 38 on the transfer gear 34 mesh at a right angle with afirst cluster gear 44 which has a first gear pin 46 for stabilizing thefirst cluster gear 44 between the frame 14 and the second cover 20. Inturn, the first cluster gear 44 drives a second cluster gear 48 whichhas a second gear pin 50 for likewise stabilizing the second clustergear 48 between the frame 14 and the second cover 20. The second clustergear 48 has a short shaft portion 52 with teeth (not shown) which engageon one side with the first cluster gear 44 and which engage on anopposite side with an output gear 56. This output gear 56 has on oneside a stepped down shaft portion 54 that is held in a cradle 72 whichis formed integrally with the second cover 20. This stepped down shaftportion 54 is formed integrally with the output shaft 58. Thus, theoutput gear 56 turns with an output shaft 58 which extends through arigid collar 2 that is formed integrally with the frame 14. This collar2 abuts against the output gear 56 and completely surrounds the outputshaft 58 so that the output shaft 58 is stronger and is capable ofapplying higher torque than a conventional shaft to a task requiringgreat strength.

[0041] Thus, a gear train extends from the driving first bevel gear 32to the driven second bevel gear 36 to the transfer gear 34 to the firstcluster gear 44 to the second cluster gear 48 to the output gear 56 andis compact because it wraps tightly around the motor 10 in the shape ofa capital letter J. Also, the gear train is contained between frame 14and the second cover 20 inside the gear box 11.

[0042] Noise generated by the gear train is suppressed by grease packedin a plurality of acoustical chambers 70 which are formed between theframe 14 and the second cover 20.

[0043] The output shaft 58 drives a tool (not shown) for crushing iceinside a refrigerator door. This output shaft 58 may also be used todrive any other electromechanical unit requiring the application of hightorque.

[0044]FIG. 7A shows a bottom plan view of the output gear 56 with thestepped down shaft portion 54 that is held in the cradle 72 seen in FIG.6. In FIG. 7A, the output gear 56 is shown to be mounted onto anintermediate shaft portion 55.

[0045]FIG. 7B shows a cross-sectional view of the output gear 56 whichis mounted on the intermediate shaft portion 55 of the output shaft 58.In regard to the output gear 56, the stepped down shaft portion 54 islocated on one side and the output shaft 58 is located on an oppositeside. Thus, the output shaft 58 engages at a right angle with the outputgear 56. The output shaft 58 includes a hollow internal chamber 59 toreceive a protuberance (not shown), such as a crank of an ice crushingdevice. A beveled interior edge 57 is formed on an outer face 53 of theshaft 58 and facilitates sliding entry of the protuberance (not shown)into the internal chamber 59 of the shaft 58.

[0046]FIG. 7C is a top plan view of the output shaft with a head on lookat the hollow internal chamber 59 thereof. This chamber 59 has ahexagonal shape, but may also have a square shape, and is formed toreceive the protuberance (not shown) which may be a hex-headed bolt. Thebeveled interior edge 57 has an annular shape between the chamber 59 andthe outer face 53 of the shaft 58.

[0047]FIG. 9A shows a bottom plan view of a second embodiment of thepresent invention. Specifically, a motor gear box 300 has a mounting tab368 formed integrally therewith at each corner. A housing 314 containsthe DC motor 10 of FIGS. 5 and 6 inside the gear box 300. Each mountingtab 368 has a rubber grommet 308 which is partially surrounded by acurved wall 306 that serves to protect the grommet 308. The purpose ofthe grommets is to minimize the noise and the vibrations caused by thehigh speed rotation of the DC motor 10 (not shown) inside the housing314. Through each grommet 308, there is a bore 310 through which a shaftof a bolt (not shown) or a threaded body of a screw (not shown) isslipped. Only a head 312 of the screw is visible in the bottom view ofFIG. 9A. For the sake of simplicity, only three of the four screw heads312 are shown in FIG. 9A.

[0048]FIG. 9B is a cross-sectional view taken along line 9B-9B of FIG.9A where the fourth screw is not shown. In FIG. 9B, the mounting tab 368has a through hole 304 in which the grommet 308 is secured bysurrounding an inner edge of the hole 304. The grommet 308 has its bore310 which allows the body of the screw or the shaft of the bolt (neithershown) to pass therethrough so as to secure the gear box 300 of FIG. 9Ato a refrigerator ice maker (not shown). However, it should be notedthat the screw or the bolt may be slipped through either end of the bore310 in the grommet 308.

[0049] Numerous modifications and variations of the present inventionare possible in light of the above teachings. Thus, it is to beunderstood that, within the scope of the appended claims, the inventionmay be practiced in ways other than as specifically described herein.

1. A motor gear box comprising: a DC motor with a permanent magnetattached thereto; a first bevel gear driven at one end by the DC motor;a second bevel gear driven by the first bevel gear; a pinion transfergear molded at one end at a right angle to the second bevel gear; atleast one cluster gear engaging at a right angle with an opposite end ofthe pinion transfer gear; an output gear driven by the at least onecluster gear; an output shaft engaging at a right angle with the outputgear; a collar abutting against the output gear and surrounding theoutput shaft; a housing containing the DC motor and having pluralmounting tabs; and a grommet secured in each of the plural mountingtabs.
 2. A motor gear box, according to claim 1, further comprising: aprogrammable control board attached to one side of the DC motor; anelectrode tip arranged on a top of the DC motor; a lead harness assemblysecured around the electrode tip; and an L-shaped connection rodconfigured to link the lead harness assembly to the programmable controlboard.
 3. A motor gear box, according to claim 1, wherein: said outputgear is mounted on an intermediate shaft portion of the output shaft. 4.A motor gear box, according to claim 1, wherein: said output shaftincludes an outer face, a hollow internal chamber, and a beveledinterior edge configured to facilitate entry into the hollow internalchamber.
 5. A motor gear box, according to claim 4, wherein: said hollowinternal chamber has a hexagonal shape; and said beveled interior edgeis formed on the outer face of the output shaft.
 6. A motor gear box,according to claim 1, further comprising: a frame formed integrally withthe collar; a first cover configured to protect the DC motor on an outerside thereof; and a second cover attached to the frame and located on aninner side of the DC motor.
 7. A motor gear box, according to claim 6,wherein: said second cover has a cradle formed integrally thereon; andsaid output shaft has a stepped down shaft portion formed integrallytherewith and configured to be held in the cradle.